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Chapter 10 The Molecular Basis of Inheritance The Molecular Basis of Inheritance.

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Presentation on theme: "Chapter 10 The Molecular Basis of Inheritance The Molecular Basis of Inheritance."— Presentation transcript:

1 Chapter 10 The Molecular Basis of Inheritance The Molecular Basis of Inheritance

2 codes for the Specific Sequence of Amino Acids in a Amino Acids determine the Protein’s Shape, which determine its Function. Proteins function as Biological Reactions Enzymes.

3 The double helix

4 Evidence of DNA Transformation - the process of transferring an inherited trait by an extract of DNA (Griffith) Mouse A is injected with live smooth pneumococcus He dies.

5 Mouse B is injected with live rough pneumococcus. He lives. The smooth pneumococcus are heat-killed and injected into Mouse C. He lives

6 Mouse D was injected with the mixture of heat-killed smooth pneumococcus and live rough pneumococcus. WHY? Transformation - transfer of genes from smooth to rough pneumonococcus

7 Smooth pneumoncoccus are virulent. Hard to kill by immune response Presence of slime capsule Rough pneumococcus are nonvirulent. Can be destroyed by immune response No slime capsule Transformation

8 Bacterial Transformation

9 5th Hour’s Incredible Work!!! Class of 2003!

10 5th Hour 2014

11 STRUCTURE OF A VIRUS *Nucleic acid core of DNA or RNA *Capsid *Envelope *Extensions, filaments, or tail fibers *Bacteriophage

12 Hershey and Chase used radioactive markers to label the protein and DNA in a bacteriophage. = protein = DNA Phages infect the bacteria

13 Intracellular Extracellular

14 Viruses infecting a bacterial cell Phage head Tail Tail fiber DNA Bacterial cell 100 nm

15 Watson & Crick

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17 Base pairing in DNA H N H O CH 3 N N O N N N NH Sugar Adenine (A) Thymine (T) N N N N Sugar O H N H N H N O H H N Guanine (G) Cytosine (C)

18 Using Franklin’s Data Purine + Purine: too wide Pyrimidine + pyrimidine: too narrow Purine + pyrimidine: width Consistent with X-ray data

19 Rosalind Franklin and her X-ray diffraction photo of DNA (a) Rosalind Franklin Franklin’s X-ray diffraction Photograph of DNA (b)

20 Complementary Base Pairing: Chargaff’s Rule AT C G A particular organism is 20% adenine then how much: T= C= G= 20% 30%

21 The double helix

22 A model for DNA replication: the basic concept (layer 4) (a) The parent molecule has two complementary strands of DNA. Each base is paired by hydrogen bonding with its specific partner, A with T and G with C. (b) The first step in replication is separation of the two DNA strands. (c) Each parental strand now serves as a template that determines the order of nucleotides along a new, complementary strand. (d) The nucleotides are connected to form the sugar-phosphate backbones of the new strands. Each “daughter” DNA molecule consists of one parental strand and one new strand. A C T A G A C T A G A C T A G A C T A G T G A T C T G A T C A C T A G A C T A G T G A T C T G A T C T G A T C T G A T C

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24 Helicase Single binding protein Replication Fork Topoisomerase

25 Helicase RNA primer Polymerase III 3’ 5’ 3’ Polymerase I 5’ 3’ 5’ RNA Primase 5’ 3’ DNA Polymerase III attaches the nucleotides in a 5’ to 3’ direction only.

26 3’ 5’3’ 5’ Polymerase III Okazaki Fragment Polymerase III DNA Ligase 3’ 5’ Polymerase I

27 Which Model of Replication????

28 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 16.17 Nucleotide excision repair of DNA damage Nuclease DNA polymerase DNA ligase A thymine dimer distorts the DNA molecule. 1 Repair synthesis by a DNA polymerase fills in the missing nucleotides. 3 DNA ligase seals the Free end of the new DNA To the old DNA, making the strand complete. 4 A nuclease enzyme cuts the damaged DNA strand at two points and the damaged section is removed. 2

29 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 16.19 Telomeres 1 µm

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32 Enzymes Involved in DNA Replication Helicase - separates the two DNA strands by making a replication fork. DNA Polymerases (III and I) - binds the free nucleotides to the unzipped strand; replaces the RNA Primer with DNA nucleotides Single Binding Proteins – keeps the unzipped strands from tangling Topoisomerase – helps relive strain in helix RNA Primase – lays down the RNA primer Ligase – bonds Okazaki fragments after primer is removed

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34 Enzymes Involved in DNA Replication

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36 Blueprint for Proteins Proteins Function as Enzymes Enzymes make Chemical Rxns Go Thus! DNA is the Blueprint for life!!

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39 Avery’s Discovery of what molecule is responsible for Transformation

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41 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 16.13 Incorporation of a nucleotide into a DNA strand New strandTemplate strand 5’ end 3’ end Sugar A T Base C G G C A C T P P P OH P P 5’ end 3’ end 5’ end A T C G G C A C T 3’ end Nucleoside triphosphate Pyrophosphate 2 P OH Phosphate

42 DNA NUCLEOTIDE = Phosphate = Deoxyribose = Adenine = Guanine = Thymine = Cytosine PurinesPyrimidines


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